Whenever my SYS light started to blink on my 96 LT4 it was the battery. It usually happened when the car was sitting for a few weeks
before I hooked up a trickle charger on it. Sounds like the same thing in your case. The battery was probably run down. I would take the car out
to charge the battery, once the battery was charged, I would disconnect the negative terminal for a few seconds to clear the code. This would
get rid of the SYS light. If it comes back on, you may need to replace the battery.
Hope this helps.